Current regulator with reinforced feedback



June 11, 1963 w. J. BONIA 3,093,800

CURRENT REGULATOR WITH REINFORCED FEEDBACK Filed May 26, 1960 HIGH LOW ,20 VOLTAGE VOLTAGE F I6. I

0 HIGH Low 2 VOLTAGE v VOLTAGE United States Patent 9 REINFORCED The present invention relates to a current regulator and more particularly to a current regulator having a reinforced feedback.

In the present day practice of research and development, often employing mammoth and complex electronic systems, there frequently arises-the need for accurate and reliable regulation of the current flowing through all, or parts, of the system. Many of these prior regulators consisted of primarily a ballast tube, seriestconnected in the circuit, or else a voltage divider network made up'of close tolerance resistors. "As a consequence, these cur; rent regulators were only moderately accurate and were relatively slow in responding to fluctuations of current.

Contrasted with these prior devices, the regulator forming the present invention offers a substantial improvement in the art. The current regulation furnished by the invention is not only very accurate and reliable, but the response time to current variations is unusually short. These features, added to the novel reinforced feedback aspect of the invention, results in an improved current regulator which is inexpensive to construct and reliable in operation.

An object regulator having a novel reinforced feedback.

Another object is the provision of a current regulator which is connected in series with the load.

Still another object is the provision of a current regulator wherein regulation is accomplished by controlling the conduction of a tube carrying the full load current.

Yet another object is the provision of a current regulator wherein variations in current apply potentials not only to a series connected regulator tube, but also to a series amplifier controlling operation of the regulator tube.

A further object is the provision of a current regulator which is responsive to the voltage drop across the ca ode resistor of the regulator tube.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 shows one embodiment of the invention.

FIG. 2 shows another embodiment of the invention.

Referring now to the drawings wherein like reference numerals designate like or corresponding parts throughout the several views, there is shown in FIG. 1 a high voltage source 11 which has connected in series with it a load 12 (in this illustration a magnetron) and a multiple element current regulator electron tube 13. Forming a part of the cathode circuit of regulator tube 13 are series connected resistors 14 and 15, the lower extremity of resistor 15 being connected back to the high voltage source 11. It will be clearly observed from the circuit of FIG. 1 that all of the current drawn by load device 12 is also carried by regulator tube 13 and resistors 14 and 15 since these elements are all series connected.

of the invention is the provision of a current located between the control grid of Patented June 11, 1963 Connected in parallel, with I and His a triode 16 having a plate load resistor 17 which further joins a source of low potential20, this potential supplying the power to operate triode 16. Additionally, regulator tube 13 and the plate of triode 16 is a first small reference battery 21, while, located between the junction .of resistors 14 and 15 and the control grid of triode .16 is a second small reference battery22. Also a connection is made between the cathode of .triode 16, the sourceof low potential 20.

and the lower terminal of resistor 15 In the operation of the embodiment shown in FIG. 1,

tube 13 isv aseries. current regulator tubehaving currentv sensing resistor 15 in its cathode. The error voltage acrossresistor15 is amplified by triode 16 and impressed on the grid of regulator tube 13 to counteract the change of current in tube 13. Reference batteries 21 and 22 set the levels of tube .13 and .tube 16 grids, respectively.

Turningnow to the preferred embodiment of the invention, illustrated in FIG. 2, there is shown the high voltage source 11, load 12, regulator tube 13 and cathode resistor 14, all connected into a series circuit as before. Forming a series amplifier are two triodes 16 and 23, the plate of tube 23 being joined to the cathode of tube 16. Supplying the potential for the amplifier is a low voltage source 20 having connected between it and the cathode of triode 23 an adjustable resistor 24, the grid of triode 23 being tied to the arm 25 of resistor 24. Between the cathode of regulator tube 13 and the control grid of triode 16 there is placed a first reference battery 26, while a second reference battery 27 is used to join the cathode of triode 23 and the control grid of regulator tube 13. To complete the circuit connections are made between the lower end of cathode resistor 14 and the junction of triodcs 16 and 23, as well as the plate of triode 16 and low voltage source 20.

In operation, the preferred embodiment of FIG. 2 functions as follows: first let it be noted that the potential of batteries 26 and 27 has been chosen to set the operation of tubes 13 and 16, at a desired level, the positive polarity of battery 27 being used to hold regulator tube 13 near zero bias, while battery 26 places a normally negative potential on the grid of tube 16. Should the current drawn by load 12 increase then the current through regulator tube 13 and cathode resistor 14 also increases. Due to the voltage drop across resistor 14 the control grid of triode 16 becomes more positive, offsetting the negative bias of battery 26, resulting in additional current being drawn by tube 16 and correspondingly passed by triode 23. As this current through tubes 16 and 23 increases the plate resistance of the tube 16 decreases, thereby causing a larger portion of the low voltage supply 20 to appear across triode 23. Under this influence the cathode of triode 23 becomes more negative with respect to its plate, thereby causing the control grid to regulator tube 13 to become more negative reducing the current passed by the tube 13. It is obvious that this operation counteracts the tendency of the current passed by the load to increase.

As has been alleged previously in the application, the present current regulator has a reinforced feedback aspect, and the adjustable resistor 24 accomplishes this function. Resistor 24 is used to set the initial potential on the grid of tube 13, but it has a more significant function: the increase of current through triode 16 makes the grid tube 13 and resistors 14 of triode 23 (through arm 25 of resistance 24) more negative causing a greater change of voltage across mode 23 than that due to the action of tube 16 alone. This part of the circuit then behaves as a constant current device, giving a wider and more linear variation of voltage across triode 23.

Triodes 16 and 23 form a series amplifier with tube 23 acting as the plate load of tube 16. The load resistance for tube 16 is given by where r and n are associated with tube 23. Since the voltage gain of tube 16 is the high value of R afforded by the negative feedback causes the gain of tube 16 to approach its maximum value, ,u. It is clearly apparent, therefore, that with this high gain of tube 16 relatively minor variations in current drawn by the load are immediately reflected in a large counteracting operation by tube 16 to correct for the variation. The extremely high gain and the simple direct coupled configuration of the present device ofiers a novel and effective current regulator with reinforced feedback.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within its connection to the adjustable the scope of the appended claim practiced otherwise than as specifically described.

What is claimed is:

A current regulator comprising a load device, a regulator tube connected to the load, a cathode resistor connected to the regulator tube so as to carry all of the current flowing through the regulator tube and load, a source of high potential joining the load and the cathode resistor, first and second triodes connected in series, a first reference battery, means connecting said first reference battery between one end of the cathode resistor and the control grid of the first triode, means connecting the other end of the cathode resistor and the juncture of the first and second triodes, a source of low potential connected to the plate of the first triode, an adjustable resistance connected to the source of low potential and the cathode of the second triode, means connecting the grid of the second triode and the sliding arm of the adjustable resistance, a second reference battery, and means connecting the second reference battery between the grid of the regulatortube and the cathode of the second triode, whereby variations in the current flowing through the cathode resistor causes an opposing potential to be applied to both the regulator tube and second triode thereby regulating the current drawn by the load.

Harness et a1 May 17, 1932 Lampe Sept. 24, 1957 the invention may be 

